1. Field of the Invention
This invention relates to a hypodermic syringe adapted to protect against accidental needle sticks.
2. Description of the Prior Art
Health professionals and others who use hypodermic syringes to inject medicine or other substances into patients or to obtain samples of blood or other bodily fluids from people are subject to risk of infection if they are stuck with a contaminated needle that has previously been used on an infected person. This is a matter of special concern when facing the possibility of dealing with patients who have infectious hepatitis or Acquired Immune Deficiency Syndrome (AIDS). The needle of a hypodermic syringe, being sharp to penetrate the skin readily for its intended purpose, can penetrate clothing and rubber gloves of the health professional using the hypodermic syringe and thus puncture the skin of the health professional. The threat of contamination is present with needles that are used for subcutaneous and intramuscular injection and needles used for intravenous injection of and for the drawing of blood or other body fluids from veins or other parts of the body. Likewise, hypodermic syringes used in dentistry also pose a threat of accidental contamination.
A hypodermic syringe is herein defined as a combination of a hollow needle or cannula having a pointed extremity and opposed mounting collar and a syringe comprised of a plunger slidingly interactive with a fluid-confining transparent barrel having an open rear extremity and apertured forward extremity equipped with a forwardly directed nipple adapted to engage the mounting collar of said needle. The barrel is typically marked with graduations to measure quantities of fluids injected or withdrawn. In some hypodermic syringes, designed for use in a vacuum withdrawal system or for dental use, the needle is normally double-ended, passing completely through the mounting collar and extending beyond the collar in both directions. The hypodermic syringe in such case serves as a support for a medication carpule having a soft plastic that is pierced by the needle, thereby enabling the plunger to dispense the contents of the carpule. In either event, the forwardly protruding pointed extremity of the needle is normally equipped with a removable cover to protect health professionals from accidental contact with the point of the needle.
For any of the uses described above, universal practice is either to discard the needle after one use, or else to sterilize it before another use. During the act of disposal, the contaminated needle is exposed between its site of use and a dispenser device. Carelessness on the part of the health professional or other user of the hypodermic, distractions occasioned by telephone calls and the like, or accidental jostling by a passersby, make it possible to bring the contaminated point of the needle into contact with the body of the health professional. A particular threat exists when the needle cover is replaced before the needle is discarded. In this case the health professional typically holds the needle cover in one hand and inserts the needle onto the cover. The same distracting factors may cause the contaminated point of the needle to come into contact with his or her hand.
U.S. patent application Ser. No. 07/711,652, filed Jun. 6, 1991 discloses a hypodermic syringe having a protective feature comprised of a hub which receives the rear extremity of the needle, and attaches to the nipple of the barrel. The hub further interacts with a cylindrical sheath in a manner whereby the point of the needle is protectively shielded following use. Although such innovation is highly effective, it has been found that manufacture of a needle whose rear extremity is embedded in a specialized hub is a very expensive endeavor.
It is accordingly an object of the present invention to provide apparatus for protectively covering the cannula needle of a hypodermic syringe before and after use of said syringe.
It is another object of this invention to provide apparatus as in the foregoing object wherein said cannula needle is of conventional design having a mounting collar.
It is a further object of the present invention to provide needle-protecting apparatus of the aforesaid nature which is simple to use and amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.